Packet steering to a host-based firewall in virtualized environments

ABSTRACT

Techniques are disclosed for redirecting network traffic of virtualized application workload to a host-based firewall. For example, a system comprises a software defined networking (SDN) controller of a multi-tenant virtualized data center configured to: receive a security policy expressed as one or more tags to redirect traffic of a virtualized application workload to a host-based firewall (HBF) of the multi-tenant virtualized data center; configure network connectivity to the HBF in accordance with the security policy; a security controller that manages the HBF configured to: obtain the one or more tags from the SDN controller; receive one or more firewall policies expressed in terms of the one or more tags, wherein each of the one or more firewall policies specifies a function of the HBF; and configure the function of the HBF in accordance with the one or more firewall policies.

This application claims the benefit of U.S. International ApplicationSerial Number PCT/CN2020/076930, filed 27 Feb. 2020 and entitled PACKETSTEERING TO A HOST-BASED FIREWALL IN VIRTUALIZED ENVIRONMENTS, theentire contents of which is hereby incorporated by reference.

TECHNICAL FIELD

This disclosure generally relates to computer networks, and morespecifically, to packet steering for a virtualized computinginfrastructure.

BACKGROUND

In a typical cloud data center environment, there is a large collectionof interconnected servers that provide computing and/or storage capacityto run various applications. For example, a data center may comprise afacility that hosts applications and services for subscribers, i.e.,customers of the data center. The data center may, for example, host allof the infrastructure equipment, such as networking and storage systems,redundant power supplies, and environmental controls. In a typical datacenter, clusters of storage systems and application servers areinterconnected via high-speed switch fabric provided by one or moretiers of physical network switches and routers. More sophisticated datacenters provide infrastructure spread throughout the world withsubscriber support equipment located in various hosting facilities.

Virtualized data centers are becoming a core foundation of the moderninformation technology (IT) infrastructure. In particular, modern datacenters have extensively utilized virtualized environments in whichvirtual hosts, such virtual machines or containers, are deployed andexecuted on an underlying compute platform of physical computingdevices.

Virtualization with large scale data center can provide severaladvantages. One advantage is that virtualization can provide significantimprovements to efficiency. As the underlying physical computing devices(i.e., servers) have become increasingly powerful with the advent ofmulticore microprocessor architectures with a large number of cores perphysical CPU, virtualization becomes easier and more efficient. A secondadvantage is that virtualization provides significant control over thecomputing infrastructure. As physical computing resources becomefungible resources, such as in a cloud-based computing environment,provisioning and management of the computing infrastructure becomeseasier. Thus, enterprise IT staff often prefer virtualized computeclusters in data centers for their management advantages in addition tothe efficiency and increased return on investment (ROI) thatvirtualization provides.

SUMMARY

In general, the disclosure describes techniques for providing a policyframework to steer network traffic of virtualized application workloadsto a host-based service, such as a host-based firewall. In somevirtualized environments, certain firewalls may provide security only upto the transport layer (e.g., layer 4 (L4)) of the Open SystemInterconnection (OSI) model. These firewalls may be referred to as L4firewalls. Other firewalls, typically referred to as next-generationfirewalls (NGFWs) or L7 firewalls, provide security for the applicationlayer (e.g., layer 7 (L7)). For example, NGFW firewalls may providefunctions, such as Intrusion Prevention Systems (IPS), IntrusionDetection Systems (IDS), anti-virus (AV), malware detection, and othersecurity functions not provided by the L4 firewalls. As furtherdescribed in this disclosure, a policy framework is provided to enableusers to define tag-based policies to integrate NGFW firewalls with L4firewalls to provide network security for a wider range of layers of theOSI model.

In one example, a centralized controller (e.g., Software DefinedNetworking (SDN) controller) provides network function virtualizationfor a multi-tenant virtualized data center to steer network traffic ofvirtualized application workloads to a NGFW, such as a host-based filter(HBF). For example, a user may use the SDN controller to specify apolicy to control network traffic of a virtualized application workload.The policy is expressed in terms of one or more tags that categorize oneor more objects of a data model for the application workload to controlnetwork traffic between the tagged objects. For instance, a user may tagobjects as applications (e.g., human resource application, financeapplication, sales application, etc.), application tiers (e.g., web,application, database), and other categorizations. A user may use thetags to define a policy for an application workload to direct traffic ofthe application workload (e.g., between a web tier and an applicationtier) and, in accordance with the techniques described in thisdisclosure, to redirect the traffic of the application workload to anHBF.

A security controller that manages the firewall policies of the HBFobtains the one or more tags from the SDN controller such that the user(or another user) may use the security controller to specify one or morefirewall policies expressed in terms of the one or more tags for theHBF. For example, the user may define a firewall policy expressed interms of the one or more tags that specifies a function for instances ofthe HBF, such as IPS, IDS, AV, malware detection, and other securityfunctions, to be applied to network traffic of the application workload.In this way, the policy framework as described herein enables a user tospecify firewall policies expressed in terms of one or more tagsrecognized by the virtual network constructs deployed in the virtualizedenvironment, therefore integrating NGFWs that may, in some instances, beprovided and managed by third-parties to the virtualized environment.

The techniques described in this disclosure may provide one or moretechnical advantages that realizes at least one practical application.For example, the policy framework described in the disclosure enablesthe integration of host-based firewalls implemented in multiplescenarios, such as a host-based firewall implemented on a virtualmachine or container, or host-based firewalls managed by third-partysecurity controllers that may not originally support tag-based policies.Moreover, the techniques of the disclosure provide intra-network servicechaining to host-based firewalls, therefore enabling host-basedfirewalls to be implemented close to application workloads and improvedperformance.

In one example, this disclosure describes a method comprising receiving,by a software defined networking (SDN) controller of a multi-tenantvirtualized data center, a security policy expressed as one or more tagsto redirect traffic of a virtualized application workload to ahost-based firewall (HBF) of the multi-tenant virtualized data center.The method also comprises configuring, by the SDN controller, a virtualrouter to direct traffic of the virtualized application workload to theHBF in accordance with the security policy. The method further comprisesobtaining, by a security controller that manages the HBF, the one ormore tags from the SDN controller. Additionally, the method comprisesreceiving, by the security controller, one or more firewall policiesexpressed in terms of the one or more tags, wherein each of the one ormore firewall policies specifies a function of the HBF. The methodfurther comprises configuring, by the security controller, the functionof the HBF in accordance with the one or more firewall policies.

In another example, this disclosure describes a system comprising asoftware defined networking (SDN) controller of a multi-tenantvirtualized data center configured to receive a security policyexpressed as one or more tags to redirect traffic of a virtualizedapplication workload to a host-based firewall (HBF) of the multi-tenantvirtualized data center; and configure network connectivity to the HBFin accordance with the security policy. The system also comprises asecurity controller that manages the HBF configured to: obtain the oneor more tags from the SDN controller; receive one or more firewallpolicies expressed in terms of the one or more tags, wherein each of theone or more firewall policies specifies a function of the HBF; andconfigure the function of the HBF in accordance with the one or morefirewall policies.

In another example, this disclosure describes a non-transitorycomputer-readable medium comprising instructions that, when executed,cause one or more processors of a multi-tenant virtualized data centerto: receive a security policy expressed as one or more tags to redirecttraffic of a virtualized application workload to a host-based firewall(HBF) of the multi-tenant virtualized data center; configure networkconnectivity to the HBF in accordance with the security policy; receiveone or more firewall policies expressed in terms of the one or moretags, wherein each of the one or more firewall policies specifies afunction of the HBF; and configure the function of the HBF in accordancewith the one or more firewall policies.

The details of one or more examples of the techniques of this disclosureare set forth in the accompanying drawings and the description below.Other features, objects, and advantages of the techniques will beapparent from the description and drawings, and from the claims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram illustrating an example network system inwhich network traffic of virtualized application workloads areredirected to host-based firewalls, in accordance with techniquesdescribed in this disclosure.

FIG. 2 is a block diagram illustrating an example implementation of thedata center of FIG. 1 in further detail.

FIG. 3 is a block diagram illustrating an example configuration of ahost-based filter, in accordance with the techniques described in thisdisclosure.

FIG. 4 illustrates an example controller operating according totechniques described in this disclosure.

FIG. 5 is a block diagram illustrating an example computing device, inaccordance with the techniques described in this disclosure.

FIG. 6 is a flowchart illustrating an example operation in accordancewith the techniques of the disclosure.

Like reference characters refer to like elements throughout the figuresand description.

DETAILED DESCRIPTION

FIG. 1 is a block diagram illustrating an example network system inwhich network traffic of virtualized application workloads areredirected to host-based firewalls, in accordance with techniquesdescribed in this disclosure. Network system 2 in the example of FIG. 1includes data centers 10A-10X (collectively, “data centers 10”)interconnected with one another and with customer networks associatedwith customers 11 via a service provider network 7. In general, eachdata center 10 provides an operating environment for applications andservices for customers 11 coupled to the data center by service providernetwork 7. Data centers 10 may, for example, host infrastructureequipment, such as networking and storage systems, redundant powersupplies, and environmental controls. Service provider network 7 may becoupled to one or more networks administered by other providers, and maythus form part of a large-scale public network infrastructure, e.g., theInternet.

In some examples, each data center 10 may represent one of manygeographically distributed network data centers. As illustrated in theexample of FIG. 1 , each of data centers 10 may be a facility thatprovides network services for customers 11. Customers 11 may becollective categories such as enterprises and governments orindividuals. For example, a network data center may host web servicesfor several enterprises and end users. Other exemplary services mayinclude data storage, virtual private networks, traffic engineering,file service, data mining, scientific- or super-computing, and so on. Insome embodiments, each of data centers 10 may be individual networkservers, network peers, or otherwise.

In this example, each of data centers 10 includes a set of storagesystems and application servers 12A-12X (herein, “servers 12”)interconnected via high-speed switch fabric 14 provided by one or moretiers of physical network switches and routers. Servers 12 function ascompute nodes of the data center. In some examples, the terms “computenodes” and “servers” are used interchangeably herein to refer to servers12. Each of servers 12 may host one or more virtual execution elementseach having at least one virtual network endpoint for one or morevirtual networks configured in the physical network. A virtual networkendpoint for a virtual network may represent one or more virtualexecution elements that share a virtual network interface for thevirtual network. The term “virtual execution element” encompassesvirtual machines (“VMs”), containers, and other virtualized computingresources that provide an (at least partially) independent executionenvironment for applications. These virtual execution elements can betenants running virtualized application workloads, and may be referredto herein as a virtualized application workload (or just applicationworkload). Each of the virtual network endpoints may use one or morevirtual network interfaces to perform packet I/O or otherwise process apacket.

Switch fabric 14 is provided by a set of interconnected top-of-rack(TOR) switches 16A-16BN (collectively, “TOR switches 16”) coupled to adistribution layer of chassis switches 18A-18M (collectively, “chassisswitches 18”). Although not shown, each of data centers 10 may alsoinclude, for example, one or more non-edge switches, routers, hubs,gateways, security devices such as firewalls, intrusion detection,and/or intrusion prevention devices, servers, computer terminals,laptops, printers, databases, wireless mobile devices such as cellularphones or personal digital assistants, wireless access points, bridges,cable modems, application accelerators, or other network devices.

In this example, TOR switches 16 and chassis switches 18 provide servers12 with redundant (multi-homed) connectivity to IP fabric 20 and serviceprovider network 7. Chassis switches 18 aggregate traffic flows andprovides high-speed connectivity between TOR switches 16. TOR switches16 may be network devices that provide layer two (e.g., MAC) and/orlayer 3 (e.g., IP) routing and/or switching functionality. TOR switches16 and chassis switches 18 may each include one or more processors and amemory, and that are capable of executing one or more softwareprocesses. Chassis switches 18 are coupled to IP fabric 20, whichperforms layer 3 routing to route network traffic between data centers10 and customers 11 by service provider network 7.

Network system 2 implements an automation platform for automatingdeployment, scaling, and operations of virtual execution elements acrossservers 12 to provide virtualized infrastructure for execution ofapplication workloads and services. For example, data centers 10 mayinclude a Software-Defined Network (“SDN”) platform to control andmanage network behavior. In some cases, an SDN platform includes alogically centralized, and in some cases, physically distributed SDNcontroller, e.g., SDN controller 23, and a distributed forwarding planein the form of virtual routers, e.g., virtual routers 13A-13N(collectively, “VRs 13”), that extend the network from physical routersand switches in the data center switch fabric into a virtual overlaynetwork hosted in virtualized servers. SDN controller 23 facilitatesoperation of one or more virtual networks within each of data centers10, such as data center 10A, in accordance with one or more examples ofthis disclosure. Virtual networks are logical constructs implemented ontop of the physical network of data center 10A. In some examples,virtual networks may be implemented on a virtual private network (VPN),virtual LAN (VLAN), or the like. In some examples, SDN controller 23 mayoperate in response to configuration input received from orchestrationengine 22, which in turn operates in response to configuration inputreceived from network administrator 24. Additional information regardingSDN controller 23 operating in conjunction with other devices of datacenter 10A or other software-defined network is found in InternationalApplication Number PCT/US2013/044378, filed Jun. 5, 2013, and entitledPHYSICAL PATH DETERMINATION FOR VIRTUAL NETWORK PACKET FLOWS, which isincorporated by reference as if fully set forth herein.

In some examples, orchestration engine 22 manages application-layerfunctions of data center 10 such as managing compute, storage,networking, and application resources executing on servers 12.“Orchestration,” in the context of a virtualized computinginfrastructure, generally refers to provisioning, scheduling, andmanaging virtual execution elements and/or applications and applicationservices executing on such virtual execution elements to the hostservers available to the orchestration platform. For example,orchestration engine 22 may attach virtual machines (VMs) to a tenant'svirtual network and generally manage the launching, migration anddeconstruction of the VMs as needed. In other examples, containerorchestration permits container coordination and refers to thedeployment, management, scaling, and configuration, e.g., of containersto host servers by a container orchestration platform. Example instancesof orchestration platforms include Kubernetes, Docker swarm,Mesos/Marathon, OpenShift, OpenStack, VMware, and Amazon ECS.

Orchestrator 22 and SDN controller 23 together implement a controllerfor the network system 2. Orchestrator 22 and SDN controller 23 mayexecute on separate computing devices or execute on the same computingdevice. Each of orchestrator 22 and SDN controller 23 may be adistributed application that executes on one or more computing devices.

In some examples, SDN controller 23 is a lower-level controller taskedwith managing the network and networking services of data center 10Aand, in particular, virtual services such as virtual firewalls ofservers 12. SDN controller 23 utilizes a set of communication protocolsto configure the network. A communication protocol may include amessaging protocol such as eXtensible Messaging and Presence Protocol(XMPP), for example. For example, SDN controller 23 implementshigh-level requests from orchestration engine 22 by configuring physicalswitches, e.g. TOR switches 16, chassis switches 18, and switch fabric14; physical routers; physical service nodes such as firewalls and loadbalancers; and virtual services such as virtual firewalls in a VM. SDNcontroller 23 maintains routing, networking, and configurationinformation within a state database. SDN controller 23 communicates asuitable subset of the routing information and configuration informationfrom the state database to virtual network (VN) agents on each ofservers 12A-12N.

In the example of FIG. 1 , network system 2 implements a scalable,multi-dimensional policy framework to support application of policiesfor controlling network traffic among application workloads executingwithin one or more computing environments for data centers 10.Application workloads may be categorized (e.g., identified) using one ormore tags. As described herein, a “tag” may refer to information used tocategorize an object of a data model for an application workloadaccording to a particular value or set of values. Tags may, in someexamples, categorize an object based on application type, applicationtier (e.g., web tier, application tier, database tier), deployment(e.g., development, QA, staging, or production stage), geographic site,user, or compliance. As one example, a user may tag objects of a financeapplication workload, such as applications (e.g., application=finance),application tiers (e.g., tier=web, tier=application).

In further examples, a user may define “labels” to be used as acustomized tag. Other examples of tags may include tags describinginfrastructure, such as a compute node, rack, groups oflogically-related elements (sometimes referred to as “pods” for someorchestration platforms, e.g., Kubemetes), cluster, or data center whichis provisioned to support the application. Tags may be predefined,implicitly assigned during provisioning, or may be customized via SDNcontroller 23 or upload tag configurations (e.g., in JSON format). Tagsmay be defined at different levels such as a global environment level, aproject level, a virtual network level, a virtual machine or containerlevel, and an interface level. In some examples, multiple tags areapplied to a single object, but the object may only have a single tagper type and/or category. Furthermore, as used herein, “tagging” anobject refers to categorizing the object in a category specified by atag included in a policy rule. Although tags are described as themechanism to categorize an object, the techniques are not limited to theuse of tags. Any mechanism to categorize an object may be utilized, andtags is one example way in which to categorize an object. Additionalexamples of tagging are described in U.S. application Ser. No.16/024,412, entitled “POLICY-DRIVEN WORKLOAD LAUNCHING BASED ON SOFTWAREDEFINED NETWORKING ENCRYPTION POLICIES,” filed Jun. 29, 2018, the entirecontents of which is incorporated by reference herein.

In some examples, the policy framework described herein permits anadministrator, e.g., administrator 24, to specify a policy expressed interms of one or more tags that categorize one or more objects of a datamodel for the application workload to control network traffic betweenthe tagged objects. In some examples, the policy rules may bepre-configured and are configured on HBFs 11 when HBFs 11 are created.

As one example, administrator 24 may use a policy controller 25 of theSDN controller 23 to define tags for objects of a finance applicationworkload. For the finance application workload, administrator 24 maydefine an application tag (e.g., application=finance) and applicationtier tags (e.g., tier=web and tier=application). Administrator 24 mayuse the tags to control traffic of the finance application workload,such as to direct traffic from a web tier to an application tier, forexample. Tagged objects of the finance application workload may be usedto define a security policy for the traffic, such as whether to allow ordeny the traffic. As another example, administrator 24 may use a policycontroller 25 to define tags for objects of a sales applicationworkload. For the sales application workload, administrator 24 maydefine an application tag (e.g., application=sales) and application tiertags (e.g., tier=web, tier=application, and tier=database).Administrator 24 may use the tags to control traffic of the salesapplication workload to direct traffic from a web tier to an applicationtier, which is then directed to a database tier. Tagged objects of thesales application workload may be used to define a security policy forthe traffic, such as whether to allow or deny the traffic. SDNcontroller 23 may send the tag-based security policies and routinginstances to servers 12 using, for example, XMPP, which installs aforwarding state into the forwarding plane of virtual routers 13.

In some examples, VMs of servers 12 are configured to provide networkservices, such as firewalls. In some instances, certain firewalls mayprovide security only up to the transport layer (e.g., layer 4). Inother words, these firewall may provide security for the physical layer(L1), data link layer (L2), network layer (L3), and transport layer(L4), but may not provide security for higher layers, such as theapplication layer (L7). These firewalls may be referred to as “L4firewalls.” Firewalls that provide security for the application layer,typically referred to as next-generation firewalls (NGFWs) or L7firewalls, may be integrated with L4 firewalls to provide protection fora wider range of layers. For example, NFGWs, such as HBFs 11A-11N(collectively, “HBFs 11”), may provide functions, such as IntrusionPrevention Systems (IPS), Intrusion Detection Systems (IDS), anti-virus(AV), malware detection, and other security functions. Although NGFWsare described herein as host-based firewalls (HBFs), NGFWs may alsoinclude physical firewalls. In the example of FIG. 1 , HBFs 11 areimplemented using a virtualized execution element, such as a VM or oneor more containers of servers 12. HBFs 11 may support various modes,such as routing, transparent, and bump-in-the-wire (BITW).

In some examples, a separate controller, such as security controller 27,manages firewall policies of HBFs 11. Without the techniques describedin this disclosure, security controllers may not support tag-basedpolicies, which may prevent HBFs managed by these security controllersfrom being integrated into a virtual environment that supports tag-basedpolicies.

In accordance with the techniques described in this disclosure, networksystem 2 provides a policy framework to enable users to define tag-basedpolicies to integrate host-based services, such as HBFs 11 (e.g., L7firewalls) with L4 firewalls. In the example of FIG. 1 , HBF 11A isimplemented on a virtual execution element (e.g., VM or container)hosted on server 12A. Similarly, HBF 11N is implemented on a virtualexecution element hosted on server 12N.

In the example of FIG. 1 , the policy framework enables administrator 24to further define the security policies to redirect network traffic toHBFs 11 to utilize functions of HBFs 11 such as IPS, IDS, AV, malwaredetection, and other security functions. In other words, policycontroller 25 is used to manage virtual network constructs to directtraffic to HBFs 11. As one example, administrator 24 may use policycontroller 25 to define a security policy to direct traffic from a webtier to an application tier of the finance application workload, andthen to redirect the traffic to HBF 11A. In this example, administrator24 may use policy controller 25 to define the security policy as:Tier=Web→Tier=App all traffic to HBF

Policy controller 25 may push the security policy to distributed policyagents executing on computing devices, e.g., servers 12, that host thefinance application workload. The policy agent for server 12A may applythe security policies to tagged objects that are members of categories(e.g., tier=web, tier=application) of the finance application workloadto redirect traffic to HBF 11A. The policy agent for server 12A may mapthe tags to ports (“tags-to-port mappings”) of virtual executionelements that implement the HBF.

Administrator 24 (or another user) may, in some instances, use differentcontroller that manages HBF 11A, e.g., security controller 27, tospecify a function (e.g., firewall policy) of HBF 11A to be applied tonetwork traffic of the finance application workload. Although policycontroller 25 and security controller 27 is illustrated in the exampleof FIG. 1 as separate controllers, policy controller 25 and securitycontroller 27 may in some instances be a single controller that managesvirtual network constructs and firewall policies of HBFs 11.

In the example of FIG. 1 , administrator 24 may use security controller27 to specify a function of HBF 11A, such as IPS to be applied totraffic of the finance application workload. In some examples, securitycontroller 27 may learn the tenants and tags from policy controller 25such that administrator 24 may use security controller 27 to configureone or more firewall policies for HBF 11A for the finance applicationworkload. For example, security controller 27 may obtain informationfrom SDN controller 23 the configuration information for an applicationworkload running on servers 12. For example, security controller 27 maycommunicate with policy controller 25 to learn about tenants, virtualnetworks, VMs belonging to the virtual networks, and any associated tagsfor the finance application workload, and uses the information abouttenants and tags to configure firewall policies (e.g., securityfunctions) for the HBF. In this example, administrator 24 may define thefirewall policy for HBF 11A to provide IPS for HTTPs traffic of thefinance application workload, as shown below:Tier=Web→Tier=App service HTTPs to IPS

In some examples, administrator 24 may use policy controller 25 todefine another firewall policy for different traffic of the financeapplication workload. For example, administrator may define a firewallpolicy for HBF 11A to provide malware detection for HTTP traffic of thefinance application workload, as shown below:Tier=Web→Tier=App service HTTP to malware detection

Distributed policy agents executing on computing devices, e.g., servers12, that host the finance application workload may then apply thesecurity policies to tagged objects that are members of categories toredirect traffic to HBF 11A and to apply the security functions providedby HBF 11A as defined by the firewall policies.

In some examples, administrator 24 may use policy controller 25 todefine a security policy for another instance of HBF 11A, such as forthe sales application workload. In this example, administrator 24 mayuse policy controller 25 to define a security policy for the virtualrouter 13A to direct traffic from a web tier to an application tier ofthe sales application workload, from the application tier to a databasetier, and then redirect the traffic to HBF 11A. In this example,administrator 24 may use policy controller 25 to define the securitypolicy to redirect traffic of the sales application workload to the HBF,as shown below:Tier=Web→Tier=App service SQL traffic to HBF

Policy controller 25 may push the security policy to distributed policyagents executing on computing devices, e.g., servers 12, that host thesales application workload. The policy agent for server 12A may applythe security policies to tagged objects that are members of categories(e.g., tier=web, tier=application, tier=database) of the salesapplication workload to redirect traffic to HBF 11A. The policy agentfor server 12A may map the tags to ports (“tags-to-port mappings”) ofvirtual execution elements that implement the HBF.

Administrator 24 may use security controller 27 to specify a function ofHBF 11A (e.g., anti-virus) to be applied to traffic of the salesapplication workload. In some examples, security controller 27 may learnthe tenants and tags from policy controller 25 such that administrator24 may use security controller 27 to configure one or more firewallpolicies for HBF 11A for the sales application workload. For example,security controller 27 may obtain information from SDN controller 23 theconfiguration information for an application workload running on servers12. For example, security controller 27 may communicate with policycontroller 25 to learn about tenants, virtual networks, VMs belonging tothe virtual networks, and any associated tags for the sales applicationworkload, and uses the information about tenants and tags to configurefirewall policies for the HBF. In examples where there are multipleinstances of HBF, the tenant information may include an identifier, suchas a virtual local area network (VLAN) identifier to determine the HBFinstance for a particular tenant. In this example, administrator 24 maydefine the firewall policy for HBF 11A to provide anti-virus protectionfor traffic of the sales application workload, as shown below:Tier=Web→Tier=App service SQL traffic to AV

Distributed policy agents executing on computing devices, e.g., servers12, that host the sales application workload may then apply the securitypolicies to tagged objects that are members of categories to redirecttraffic to HBF 11A and to apply the security functions provided by HBF11A as defined by the firewall policies.

FIG. 2 is a block diagram illustrating an example implementation of datacenter 10A of FIG. 1 in further detail. In the example of FIG. 2 ,virtual routers 30 dynamically create and manage one or more virtualnetworks 34 usable for communication between application instances. Inone example, virtual routers 30 execute the virtual network as anoverlay network, which provides the capability to decouple anapplication's virtual address from a physical address (e.g., IP address)of the one of servers 12A-12X (“servers 12”) on which the application isexecuting. Each virtual network may use its own addressing and securityscheme and may be viewed as orthogonal from the physical network and itsaddressing scheme. Various techniques may be used to transport packetswithin and across virtual networks 34 over the physical network.

Each virtual router 30 may execute within a hypervisor, a host operatingsystem or other component of each of servers 12. Each of servers 12 mayrepresent an x86 or other general-purpose or special-purpose servercapable of executing virtual machines 36. In the example of FIG. 2 ,virtual router 30A executes within hypervisor 31, also often referred toas a virtual machine manager (VMM), which provides a virtualizationplatform that allows multiple operating systems to concurrently run onone of servers 12. In the example of FIG. 2 , virtual router 30A managesvirtual networks 34 (e.g., VN0-VN2), each of which provides a networkenvironment for execution of one or more virtual machines (VMs) 36 ontop of the virtualization platform provided by hypervisor 31. Each VM 36is associated with one of the virtual networks VN0-VN2 and may representtenant VMs running customer applications such as Web servers, databaseservers, enterprise applications, or hosting virtualized services usedto create service chains. In some cases, any one or more of servers 12or another computing device may host customer applications directly,i.e., not as virtual machines. In some cases, some of VMs 36 mayrepresent containers, another form of virtualized execution environment.That is, both virtual machines and container are examples of virtualizedexecution environments for executing application workloads.

In general, each VM 36 may be any type of software application and maybe assigned a virtual address for use within a corresponding virtualnetwork 34, where each of the virtual networks may be a differentvirtual subnet provided by virtual router 30A. A VM 36 may be assignedits own virtual layer three (L3) IP address, for example, for sendingand receiving communications but may be unaware of an IP address of thephysical server 12A on which the virtual machine is executing. In thisway, a “virtual address” is an address for an application that differsfrom the logical address for the underlying, physical computer system,e.g., server 12A in the example of FIG. 1 or 2 .

In one implementation, each of servers 12 includes a corresponding oneof virtual network (VN) agents 35A-35X (collectively, “VN agents 35”)that controls virtual networks 34 and that coordinates the routing ofdata packets within server 12. In general, each VN agent 35 communicateswith virtual SDN controller 23, which generates commands to controlrouting of packets through data center 10A. VN agents 35 may operate asa proxy for control plane messages between virtual machines 36 and SDNcontroller 23. For example, a VM 36 may request to send a message usingits virtual address via the VN agent 35A, and VN agent 35A may in turnsend the message and request that a response to the message be receivedfor the virtual address of the VM 36 that originated the first message.In some cases, a VM 36 may invoke a procedure or function call presentedby an application programming interface of VN agent 35A, and the VNagent 35A may handle encapsulation of the message as well, includingaddressing. In accordance with the techniques of the disclosure, each VNagent 35 further includes a respective policy agent 139A-139X(collectively, policy agents 139″) for applying one or more securitypolicies and one or more firewall policies to one or more categories, aswill described in more detail below.

In one example, network packets, e.g., layer three (L3) IP packets orlayer two (L2) Ethernet packets generated or consumed by the instancesof applications executed by virtual machines 36 within the virtualnetwork domain may be encapsulated in another packet (e.g., another IPor Ethernet packet) that is transported by the physical network. Thepacket transported in a virtual network may be referred to herein as an“inner packet” while the physical network packet may be referred toherein as an “outer packet” or a “tunnel packet.” Encapsulation and/orde-capsulation of virtual network packets within physical networkpackets may be performed within virtual routers 30, e.g., within thehypervisor or the host operating system running on each of servers 12.As another example, encapsulation and de-capsulation functions may beperformed at the edge of switch fabric 14 at a first-hop TOR switch 16that is one hop removed from the application instance that originatedthe packet. This functionality is referred to herein as tunneling andmay be used within data center 10A to create one or more tunnels forinterconnecting servers 12. Besides IPinIP, other example tunnelingprotocols that may be used include IP over GRE, VxLAN, MPLS over GRE,MPLS over UDP, etc.

As noted above, SDN controller 23 provides a logically centralizedcontroller for facilitating operation of one or more virtual networkswithin data center 10A. SDN controller 23 may, for example, maintain arouting information base, e.g., one or more routing tables that storerouting information for the physical network as well as one or morenetworks of data center 10A. Similarly, switches 16, 18 and virtualrouters 30 maintain routing information, such as one or more routingand/or forwarding tables. In one example implementation, virtual router30A of hypervisor 31 implements a network forwarding table (NFT) 32 foreach virtual network 34. In general, each NFT 32 stores forwardinginformation for the corresponding virtual network 34 and identifieswhere data packets are to be forwarded and whether the packets are to beencapsulated in a tunneling protocol, such as with a tunnel header thatmay include one or more headers for different layers of the virtualnetwork protocol stack.

In one or more examples, SDN controller 23 further includes policycontroller 25. Policy controller 25 is configured to tag a plurality ofobjects of virtualized application workloads. In some examples, policycontroller 25 tags the plurality of objects across a plurality ofcategories including applications executing within VMs 36, deployments,application tiers, geographic sites, virtual networks 34, interfaces,projects, security requirements, quality requirements, users, orcompliance requirements. In further examples, policy controller 25 tagsthe plurality of objects across a plurality of levels includes a levelof an object, such as a global environment level, a project level, avirtual network level, a virtual machine level, or an interface level ofthe object.

In some examples, policy controller 25 configures one or more securitypolicies expressed in terms of the tags. Policy controller 25 furtherdistributes, to respective policy agents 139 of VN agents 35, the one ormore security policies. Each security policy includes one or more policyrules for controlling network traffic, such as between virtual networks34 and to redirect traffic to a host-based filter implemented in one ofVMs 36. Each policy rule specifies one or more tags, each tag furtherspecifying one or more dimensions of the categories.

Upon receiving the one or more policies, each policy agent 139 appliesthe one or more policy rules of each of the security policies to taggedobjects to control network traffic between the tagged objects. Forexample, policy agents 139 under the direction of policy controller 25express the one or more policy rules at VNs 34 and VMs 36 that aretagged. In accordance with the techniques of this disclosure, the one ormore policy rules may redirect traffic to a host-based service, such asa host-based filter implemented on one of VMs 36 (e.g., VM4), to utilizefunctions of a host-based filter (e.g., HBF 11A of FIG. 1 ) includingIPS, IDS, AV, malware detection, and other security functions.

As an illustration of the above, in the example of FIG. 2 , policycontroller 25 creates security policies for application workloads. Forinstance, an administrator may use policy controller 25 to tag virtualmachine VM0 36 with an application tag 1 (e.g., application=finance),tag virtual network VN0 34 with an application tier tag 2 for a web tier(e.g., tier=web), and tag virtual network VN1 34 with an applicationtier tag 2 for an application tier (e.g., tier=application). Using thetags, the administrator uses policy controller 25 to configure asecurity policy for the finance application workload. For example, theadministrator may configure a policy for virtual router 30A to directtraffic of a web tier to an application tier of the finance applicationworkload, and to redirect the traffic to the HBF (e.g., https-traffictier=web→tier=app all traffic to HBF).

Policy controller 25 of SDN controller 23 may push the security policyto policy agent 139A of VN agent 35A to apply the security policies totagged objects that are members of categories (e.g., tier=web,tier=application) of the application workload to redirect traffic to HBF11A. For example, policy agent 139A connects virtual networks VN0 34 andVN1 34, and configures virtual router 30A with a tag-to-port mapping toredirect traffic of tagged virtual networks VN0 34 and VN1 34 tointerfaces (e.g., input and output interfaces) of VM4 36 that implementsthe HBF. For example, policy agent 139A configures within virtual router30A a map of Virtual Routing and Forwarding (VRF) to interfaces of theHBF.

Policy agent 139A may communicate tenant information and the tag-to-portmapping to SDN controller 23, which stores it in a configurationdatabase. As described below, security controller 27 may obtain thetenant information and the tag-to-port mapping from policy controller25.

The administrator uses security controller 27 to specify a function,e.g., firewall policy, of the HBF implemented on VM4 36 to be applied totraffic of the finance application workload. Security controller 27 mayobtain from SDN controller 23 configuration information (e.g., tenantsand tags) for an application workload running on servers 12. As oneexample, security controller 27 may obtain configuration informationfrom SDN controller 23 periodically and/or based on events (e.g., whenvirtual machines are instantiated). In some examples, securitycontroller 27 may obtain configuration information using a peeringsession (e.g., BGP) with SDN controller 23.

Security controller 27 may convert the tags to IP addresses for whichsecurity functions are to be applied by the HBF, and may push thefirewall policies to the HBF. As one example, the administrator mayspecify the HBF to provide an IPS for HTTPs traffic of the financeapplication workload. In another example, the administrator may specifythe HBF to provide malware protection for HTTP traffic of the financeapplication workload. Security controller 27 may push the firewallpolicies, using XMPP or Network Configuration Protocol (NETCONF), forexample, to configure the HBF to provide the various functions fortraffic of the finance application workload. In this way, the securitycontroller 27 may configure firewall policies expressed in terms of tagsthat support the finance application workload categorized using one ormore tags.

As another example, the administrator may use orchestration engine 22 totag virtual machine VM1 36 with an application tag 3 (e.g.,application=sales), tag virtual network VN0 34 with an application tiertag 4 for a web tier (e.g., tier=web), tag virtual network VN1 34 withan application tier tag 4 for an application tier (e.g.,tier=application), and tag virtual network VN2 34 with an applicationtier tag 4 for a database tier (e.g., tier=database).

Using the tags, policy controller 25 configures a security policy forthe sales application workload. For example, the administrator mayconfigure a policy for the sales application workload to direct trafficfrom a web tier to the application tier, direct traffic from theapplication tier to the database tier, and to redirect the traffic tothe HBF (e.g., https-traffic tier=web→tier=app service SQL traffic toHBF).

Policy controller 25 of SDN controller 23 may push the security policyto policy agent 139A of VN agent 35A to apply the security policies totagged objects that are members of categories (e.g., tier=web,tier=application, tier=database) of the application workload to redirecttraffic to HBF 11A. For example, policy agent 139A connects virtualnetworks VN0 34-VN2 34, and configures virtual router 30A with atag-to-port mapping to redirect traffic of tagged virtual networks VN034 and VN1 34, from VN1 34 to VN2 34, and redirect the traffic tointerfaces (e.g., input and output interfaces) of VM4 36 that implementsthe HBF. For example, policy agent 139A configures within virtual router30A a map of Virtual Routing and Forwarding (VRF) to interfaces of theHBF.

Policy agent 139A may communicate tenant information and the tag-to-portmapping to SDN controller 23, which stores it in a configurationdatabase. In examples where there are multiple instances of HBF, thetenant information may include an identifier, such as a virtual localarea network (VLAN) identifier to determine the HBF instance for aparticular tenant.

Security controller 27 may obtain from SDN controller 23 configurationinformation (e.g., tenants and tags) for an application workload runningon servers 12. As described above, security controller 27 may obtainconfiguration information from SDN controller 23 periodically, and/orbased on events (e.g., when virtual machines are instantiated). In someexamples, security controller 27 may obtain configuration using apeering session (e.g., BGP) with SDN controller 23.

Security controller 27 may convert the tags to IP addresses for whichsecurity functions are to be applied by the HBF, and may push thefirewall policies to the HBF. As one example, the administrator may usesecurity controller 27 to configure the HBF to provide an anti-virus forthe IP traffic of the sales application workload. Security controller 27may push the firewall policies, using XMPP or NETCONF, for example, toconfigure the HBF to provide the various functions for traffic of thesales application workload. In this way, the security controller 27 mayconfigure firewall policies expressed in terms of tags that support thesales application workload categorized using one or more tags.

FIG. 3 is a block diagram illustrating an example configuration of ahost-based filter, in accordance with the techniques described in thisdisclosure. In the example of FIG. 3 , administrator 24 uses SDNcontroller 23 to specify a service template used to instantiate HBF 11A.Within the service template, administrator 24 may select a service mode(e.g., routing, transparent, bump-in-the-wire), an image name for thevirtual execution element (e.g., VM or container) that implements HBF11A, and interfaces for HBF 11A. The interfaces may include a leftinterface 312, a right interface 314, and a management interface 316 ofthe virtual execution element that implements HBF 11A. The SDNcontroller 23 pushes the service configuration information to VN agent35 of server 12A.

VN agent 35A of server 12A receives service configuration informationfrom SDN controller 23 and configures a virtual execution element (e.g.,VM or container) and the interfaces of the virtual execution element toimplement HBF 11A.

In the example of FIG. 3 , VN agent 35A creates a left virtual network322, a right virtual network 324, and a management virtual network 326for HBF 11A. Virtual networks 322-324 are used to direct traffic to HBF11A. VN agent 35A associates the left interface 312 with left virtualnetwork 322, the right interface 314 with right virtual network 324, andthe management interface 316 with management network 326.

Policy controller 25 configures one or more security policies to directtraffic between left virtual network 322 and right virtual network 324,and through HBF 11A. As described in this disclosure, the securitypolicies may be expressed in terms of tagged objects. In accordance withthe techniques described in this disclosure, policy controller 25configures one or more security policies expressed in terms of tags toredirect traffic between left virtual network 322 and right virtualnetwork 324 and through HBF 11A. For example, administrator 24 mayselect the virtual execution element (e.g., VM or container)implementing HBF 11A, select virtual network 322 for the left interface312, and select virtual network 314 for the right interface 314 to whichthe security policy applies. Administrator 24 may then associate thesecurity policy with left virtual network 322 and right virtual network324 to which the security policy applies. In this way, HBF 11A may beprovided as part of an intra-network service chain.

Administrator 24 (or another user) may use security controller 27 toconfigure firewall policies for HBF 11A. As described above, securitycontroller 27 may obtain the tenant information and associated tags fromSDN controller 23. Security controller 27 may convert the tags to IPaddresses for which security functions are to be applied by the HBF. Inthis way, an administrator 24 may use security controller 27 to specifyfunctions of HBF 11A, such as Intrusion Prevention Systems (IPS),Intrusion Detection Systems (IDS), anti-virus (AV), malware detection,and other security functions to be applied to tagged objects ofapplication workloads. Security controller 27 may use a configurationprotocol, such as XMPP or NETCONF to communicate with a managementinterface 316 of HBF 11A to configure HBF 11A to provide the specifiedsecurity functions.

FIG. 4 illustrates an example controller operating according totechniques described in this disclosure. SDN controller 400 mayrepresent an example instance of SDN controller 23 of FIGS. 1-3 .Although illustrated and described as a physically distributed and“virtual” network controller, some examples of VNC 400 may be bothphysically and logically centralized within an appliance or server.

As illustrated in the example of FIG. 4 , virtual network controller(VNC) 400 includes one or more virtual network controller (“VNC”) nodes402A-402N (collectively, “VNC nodes 402”) to execute the functionalityof an SDN controller, including managing the operation of virtualrouters for one or more virtual networks implemented within the datacenter. Each of VNC nodes 402 may represent a different network deviceof the data center, e.g., servers 12 of FIG. 1-3 . In some instances,some of VNC nodes 402 may execute as separate virtual machines on thesame network device.

Each of VNC nodes 402 may control a different, non-overlapping set ofdata center elements, such as network devices, individual virtualrouters executing within network devices, individual interfacesassociated with virtual routers, chassis switches, TOR switches, and/orcommunication links. VNC nodes 402 peer with one another according to apeering protocol operating over network 460. Network 460 may representan example instance of switch fabric 14 and/or IP fabric 20 of FIG. 1 .In the illustrated example, VNC nodes 402 peer with one another using aBorder Gateway Protocol (BGP) implementation, an example of a peeringprotocol. In this sense, VNC nodes 402A and 302N may represent a firstcontroller node device and a second controller node device,respectively, peered using a peering protocol. VNC nodes 402 includerespective network discovery modules 414-414N to discover networkelements of network 460.

VNC nodes 402 provide, to one another using the peering protocol,information related to respective elements of the virtual networkmanaged, at least in part, by the VNC nodes 402. For example, VNC node402A may manage a first set of one or more network devices operating asvirtual routers for the virtual network. VNC node 402A may sendinformation relating to the management or operation of the first set ofnetwork devices to VNC node 402N by BGP 418A. Other elements managed byVNC nodes 402 may include network controllers and/or appliances, networkinfrastructure devices (e.g., L2 or L3 switches), communication links,firewalls, and VNC nodes 402 for example. Because VNC nodes 402 have apeer relationship, rather than a master-slave relationship, informationmay be sufficiently easily shared among the VNC nodes 402. In addition,hardware and/or software of VNC nodes 402 may be sufficiently easilyreplaced, providing satisfactory resource fungibility.

SDN controller 400 may perform any one or more of the illustratedvirtual network controller operations represented by modules 430, whichmay include orchestration 432, user interface 434, VNC global loadbalancing 436, and one or more applications 438. SDN controller 400executes orchestration module 432 to facilitate the operation of one ormore virtual networks in response to a dynamic demand environment by,e.g., spawning/removing virtual machines in data center network devices,adjusting computing capabilities, allocating network storage resources,and modifying a virtual topology connecting virtual routers of a virtualnetwork. VNC global load balancing 436 executed by SDN controller 400supports load balancing of analytics, configuration, communicationtasks, e.g., among VNC nodes 402. Applications 438 may represent one ormore network applications executed by VN nodes 402 to, e.g., changetopology of physical and/or virtual networks, add services (e.g., addingan HBF), or affect packet forwarding.

User interface 434 includes an interface usable by an administrator (orsoftware agent) to control the operation of VNC nodes 402. For instance,user interface 434 may include methods by which an administrator maymodify, e.g. configuration database 410A of VNC node 402A.Administration of the one or more virtual networks operated by SDNcontroller 400A may

proceed by uniform user interface 434 that provides a single point ofadministration, which may

reduce an administration cost of the one or more virtual networks.

Each of VNC nodes 402 may include substantially similar components forperforming substantially similar functionality, said functionality beingdescribed hereinafter primarily with respect to VNC node 402A. VNC node402A may include a control plane virtual machine (VM) 412A that executescontrol plane protocols to facilitate the distributed VNC techniques.Control plane VM 312A may in some instances represent a native process.Control VM 312A executes BGP 318A to provide information related to thefirst set of elements managed by VNC node 402A to, e.g., control planevirtual machine 412N of VNC node 402N. Control plane VM 412A may use anopen standards based protocol (e.g., BGP based L3VPN) to distributeinformation about its virtual network(s) with other control planeinstances and/or other third party networking

equipment(s). Given the peering based model according to one or moreaspects described herein,

different control plane instances (e.g., different instances of controlplane VMs 412A-412N) may execute different software versions. In one ormore aspects, e.g., control plane VM 412A

may include a type of software of a particular version, and the controlplane VM 412N may include a different version of the same type ofsoftware. The peering configuration of the control

node devices may enable use of different software versions for thecontrol plane VMs 412A-412N. The execution of multiple control plane VMsby respective VNC nodes 402 may prevent

the emergence of a single point of failure.

Control plane VM 412A communicates with virtual routers, e.g.,illustrated virtual router

474 executed by server 470, using a communication protocol operatingover network 460. Server 470 may represent an example instance of server12 of FIGS. 1-3 . Virtual routers facilitate overlay networks in the oneor more virtual networks. In the illustrated example, control plane VM412A uses eXtensible Messaging and Presence Protocol (XMPP) 416A tocommunicate with at least virtual router 474 by XMPP interface 450.Virtualrouter data, statistics collection, logs, and configuration informationmay in accordance with XMPP 416A be sent as XML documents forcommunication between control plane VM 412A and the virtual routers.Control plane VM 412A may in turn route data to other XMPP servers(such as an analytics collector) or may retrieve configurationinformation on behalf of one or more virtual routers. Control plane VM412A may further execute a communication interface444A for communicating with configuration virtual machine (VM) 408Aassociated with configuration database 410A. Communication interface444A may represent an IF-MAP interface.

VNC node 402A may include configuration VM 408A to store configurationinformation for the first set of elements in configuration database410A. Configuration VM 408A, although described as a virtual machine,may in some aspects represent a native process executing on an operatingsystem of VNC node 402A. Configuration database 410A may storeconfiguration information related to a first set of elements managed byVNC node 402A. For example, configuration database 410A may storecontents of a high-level data model (e.g., the configuration state thatwas explicitly installed by the provisioning system) and contents of alow-level data model (e.g., the configuration state derived from thehigh-level data model). Control plane components of VNC node 402A maystore configuration information to configuration database 410A usinginterface 444A, which may represent an Interface for Metadata AccessPoints (IF-MAP) protocol implementation. VNC node 402A may share atleast some configuration information related to one or more of the firstset of elements managed by VNC node 402A and stored in configurationdatabase 410A, as well as to receive at least some configurationinformation related to any of the elements managed by others of VNCnodes 402. Configuration database 410A may represent a distributed hashtable (DHT), for instance, or any suitable data structure for storingconfiguration information for network elements in a distributed mannerin cooperation with others of VNC nodes 402. Configuration VM 408A andcontrol plane VM 412A may communicate using IF-MAP by communicationinterface 444A and using XMPP by communication interface 446A. In someaspects, configuration VM 408A may include a horizontally scalablemulti-tenant IF-MAP server and a distributed hash table (DHT)-basedIF-MAP database that represents configuration database 410A. In someaspects, configuration VM 408A may include a configuration translator,which may translate a user friendly higher-level virtual networkconfiguration to a standards based protocol configuration (e.g., a BGPL3VPN configuration), which may be stored using configuration database410A.

Communication interface 440 may include an IF-MAP interface forcommunicating with

other network elements. The use of the IF-MAP may make the storage andmanagement of virtual network configurations very flexible andextensible given that the IF-MAP schema can be

dynamically updated. Advantageously, aspects of SDN controller 400 maybe flexible for new

applications 438.

VNC node 402A may further include an analytics virtual machine (VM) 404Ato store

diagnostic information (and/or visibility information) related to atleast the first set of elements

managed by VNC node 402A. Control plane VM 412 and analytics VM 404 maycommunicate

using an XMPP implementation by communication interface 446A. AnalyticsVM 404A, although described as a virtual machine, may in some aspectsrepresent a native process executing on an operating system of VNC node402A.

VNC node 402A may include an analytics database 406A for storingdiagnostic information related to a first set of elements managed by VNCnode 402A. VNC node 402A may share at least some diagnostic informationrelated to one or more of the first set of elements managed by VNC node402A and stored in analytics database 406, as well as to receive atleast some diagnostic information related to any of the elements managedby others of VNC nodes 402. Analytics database 406A may represent adistributed hash table (DHT), for instance, or any suitable datastructure for storing diagnostic information for network elements in adistributed manner in cooperation with others of VNC nodes 402. Thedistributed database may include an XMPP interface on a first side and aREST/JSON/XMPP interface on a second side.

Virtual router 474 may implement the layer 3 forwarding and policyenforcement point

for one or more end points and/or one or more hosts. The one or more endpoints and/or one or more hosts may be classified into a virtual networkdue to configuration from control plane VM 412A. Control plane VM 412Amay also distribute virtual-to-physical mapping for each end point toall other end points as routes. These routes may give the next hopmapping virtual IP tophysical IP and encapsulation technique used (e.g., one of IPinIP,NVGRE, VXLAN, etc.). Virtual router 474 may be agnostic to actualtunneling encapsulation used. Virtual router 474 may also trapinteresting layer 2 (L2) packets, broadcast packets, and/or implementproxy for the packets, e.g. using one of Address Resolution Protocol(ARP), Dynamic Host ConfigurationProtocol (DHCP), Domain Name Service (DNS), etc. Virtual router 474 mayalso facilitate an intra-network service chain between virtual networksand through an HBF, e.g., HBF 480, as described in this disclosure.

In accordance with the techniques described in this disclosure, anadministrator may create, for example, a project for an applicationworkload using orchestration module 432 via user interface 434. SDNcontroller 400 stores the project in configuration database 410A. Theadministrator then creates configuration objects of a high-level datamodel for the project, such as such as host-based firewall 11A describedin the examples of FIGS. 1-3 , using orchestration module 432. Theobjects for HBFs (illustrated in FIG. 4 as HBF objects 411A-411N) arestored in configuration databases 410.

VNC node 402A may share configuration information related to HBF objects411 that are stored in configuration databases 410. For example, controlplane VM 412A may execute a communication interface 444A forcommunicating with configuration VM 408A to obtain configurationinformation stored in configuration database 410A, such as configurationinformation related to HBF object 411A. Control plane VM 412A may useXMPP 416A to communicate the configuration information related to HBFobject 411A to VN agent 472 of server 470. VN agent 472 uses theconfiguration information related to HBF object 411A to instantiate HBFobject 411A within server 470. For example, VN agent 472 may instantiateHBF object 411A on a virtual execution element (e.g., virtual machine orcontainer) of server 470, represented as HBF 480.

The administrator may configure a security policy to redirect traffic tothe HBF, e.g., HBF 480. For example, the administrator may configure asecurity policy expressed in terms of one or more tags that categorizeone or more objects of a data model for the application workload tocontrol network traffic between the tagged objects. The administratoruses user interface 434 to create and manage the one or more tags. Thetagged objects are stored in configuration database 410A. Theadministrator may configure a security policy expressed as taggedobjects via policy controller 437. As described above, the administratormay configure a security policy that redirects traffic from virtualnetworks of server 470 to HBF 480.

The administrator may also use security controller 439 to create andmanage firewall policies of HBF 480. Although security controller 439 isillustrated as a separate controller (e.g., for controllers that managethird-party host-based services), security controller 439 may in someinstances be included in modules 430 of SDN controller 400.

In the example of FIG. 4 , the administrator may use security controller439 to configure a firewall policy that specifies the function in whichHBF 480 is to apply to network traffic of application workloads hostedon server 470. For example, security controller 439 may obtain theconfiguration information for an application workload running on server470. Configuration information may include tenant information, virtualnetworks, virtual machines associated with the virtual networks, and/orthe associated tags. As one example, SDN controller 400 may, in responseto configuring a VM for an application workload, generate a User VisibleEntity (UVE) towards analytics VM 404A, which may access theconfiguration information stored in configuration database 410A. A usermay access or subscribe to the UVE to obtain configuration informationof an application workload, such as the virtual networks, virtualmachines that belong to the virtual networks, associated tags, and/or IPaddresses associated with the VMs. As one example, security controller439 may use an application programming interface (API) to obtain theconfiguration information from SDN controller 400. Security controller439 may periodically obtain the configuration information, or obtain theconfiguration based on an event (e.g., when VMs of an applicationworkload is instantiated). In some examples, security controller 439 mayuse a peering session, e.g., BGP, to communicate with SDN controller400.

Security controller 439 may convert the tags to IP addresses for whichsecurity functions are to be applied by HBF 480, and may push thefirewall policies to HBF 480. The administrator may then use securitycontroller 439 to create and manage firewall policies to be configuredon HBF 480. Security controller 439 may use a configuration protocol,such as XMPP or NETCONF, to communicate with a management interface ofHBF 480 using Network Configuration Protocol (NETCONF) or otherconfiguration protocols.

FIG. 5 is a block diagram illustrating an example computing device, inaccordance with the techniques described in this disclosure. Computingdevice 500 may represent an example instance of any of servers 12 ofFIGS. 1-3 and server 470 of FIG. 4 .

Computing device 500 includes in this example a system bus 542 couplinghardware components of a computing device 100 hardware environment.System bus 542 couples memory 544, network interface cards (NICs)506A-506B (collectively, “NICs 506”), storage disk 507, and multi-corecomputing environment 502 having a plurality of processing cores508A-508J (collectively, “processing cores 508”). Network interfacecards 506 include interfaces configured to exchange packets using linksof an underlying physical network.

Multi-core computing environment 502 may include any number ofprocessors and any number of hardware cores. Each of processing cores508 each includes an independent execution unit to perform instructionsthat conform to an instruction set architecture for the core. Processingcores 508 may each be implemented as separate integrated circuits (ICs)or may be combined within one or more multi-core processors (or“many-core” processors) that are each implemented using a single IC(i.e., a chip multiprocessor).

Disk 507 represents computer readable storage media that includesvolatile and/or non-volatile, removable and/or non-removable mediaimplemented in any method or technology for storage of information suchas processor-readable instructions, data structures, program modules, orother data. Computer readable storage media includes, but is not limitedto, random access memory (RAM), read-only memory (ROM), EEPROM, flashmemory, CD-ROM, digital versatile discs (DVD) or other optical storage,magnetic cassettes, magnetic tape, magnetic disk storage or othermagnetic storage devices, or any other medium that can be used to storethe desired information and that can be accessed by cores 508.

Main memory 544 includes one or more computer-readable storage media,which may include random-access memory (RAM) such as various forms ofdynamic RAM (DRAM), e.g., DDR2/DDR3 SDRAM, or static RAM (SRAM), flashmemory, or any other form of fixed or removable storage medium that canbe used to carry or store desired program code and program data in theform of instructions or data structures and that can be accessed by acomputer. Main memory 544 provides a physical address space composed ofaddressable memory locations.

Memory 544 may in some examples present a non-uniform memory access(NUMA) architecture to multi-core computing environment 502. That is,cores 508 may not have equal memory access time to the various storagemedia that constitute memory 544. Cores 508 may be configured in someinstances to use the portions of memory 544 that offer the lowest memorylatency for the cores to reduce overall memory latency.

In some instances, a physical address space for a computer-readablestorage medium may be shared among one or more cores 508 (i.e., a sharedmemory). For example, cores 508A, 508B may be connected via a memory bus(not shown) to one or more DRAM packages, modules, and/or chips (alsonot shown) that present a physical address space accessible by cores508A, 508B. While this physical address space may offer the lowestmemory access time to cores 508A, 508B of any of portions of memory 544,at least some of the remaining portions of memory 544 may be directlyaccessible to cores 508A, 508B. One or more of cores 508 may alsoinclude an L1/L2/L3 cache or a combination thereof. The respectivecaches for cores 508 offer the lowest-latency memory access of any ofstorage media for the cores 508.

Memory 544, network interface cards (NICs) 506A-506B (collectively,“NICs 506”), storage disk 507, and multi-core computing environment 502provide an operating environment for a software stack that executes avirtual router 520 and one or more virtual machines 510A-510K(collectively, “virtual machines 510”). Virtual router 520 may representexample instances of any of virtual routers 30 of FIGS. 2-3 or virtualrouter 474 of FIG. 4 . Virtual machines 510 may represent exampleinstances of any of virtual machines 36 of FIG. 2 . The computing device500 partitions the virtual and/or physical address space provided bymain memory 544 and in the case of virtual memory by disk 507 into userspace 511, allocated for running user processes, and kernel space 512,which is protected and generally inaccessible by user processes. Anoperating system kernel (not shown in FIG. 5 ) may execute in kernelspace and may include, for example, a Linux, Berkeley SoftwareDistribution (BSD), another Unix-variant kernel, or a Windows serveroperating system kernel, available from Microsoft Corp. Computing device500 may in some instances execute a hypervisor to manage virtualmachines 510 (also not shown in FIG. 5 ). An example hypervisor 31 isillustrated in FIG. 2 . Example hypervisors include Kernel-based VirtualMachine (KVM) for the Linux kernel, Xen, ESXi available from VMware,Windows Hyper-V available from Microsoft, and other open-source andproprietary hypervisors. In some examples, specialized hardwareprogrammed with routing information such as FIBs 524 may execute thevirtual router 520.

Eth0 114A and Eth1 514B represent devices according to a software devicemodel and provide device driver software routines for handling packetsfor receipt/transmission by corresponding NICs 506. Packets received byNICs 506 from the underlying physical network fabric for the virtualnetworks may include an outer header to allow the physical networkfabric to tunnel the payload or “inner packet” to a physical networkaddress for one of NICs 506. The outer header may include not only thephysical network address but also a virtual network identifier such as aVxLAN tag or Multiprotocol Label Switching (MPLS) label that identifiesone of the virtual networks as well as the corresponding routinginstance 522. An inner packet includes an inner header having adestination network address that conform to the virtual networkaddressing space for the virtual network identified by the virtualnetwork identifier. For example, virtual router forwarding plane 528 mayreceive by Eth1 from NIC 506 a packet having an outer header thanincludes a VxLAN associated in virtual router forwarding plane 528 withrouting instance 522A. The packet may have an inner header having adestination network address that is a destination address of VM 510Athat taps, via tap interface 546A, into routing instance 522A.

Virtual router 520 in this example includes a kernel space 512 module:virtual router forwarding plane 528, as well as a user space 511 module:VN agent 535. Virtual router forwarding plane 528 executes the“forwarding plane” or packet forwarding functionality of the virtualrouter 520 and VN agent 535 executes the “control plane” functionalityof the virtual router 520. VN agent 535 may represent an exampleinstance of any of VN agents 35 of FIG. 2-3 and VN agent 472 of FIG. 4 .

Virtual router forwarding plane 528 includes multiple routing instances522A-522C (collectively, “routing instances 522”) for correspondingvirtual networks. Each of routing instances 522 includes a correspondingone of forwarding information bases (FIBs) 524A-524C (collectively,“FIBs 524”) and flow tables 526A-526C (collectively, “flow tables 526”).Although illustrated as separate data structures, flow tables 526 may insome instances be logical tables implemented as a single table or otherassociative data structure in which entries for respective flow tables526 are identifiable by the virtual network identifier (e.g., a VRFidentifier such as VxLAN tag or MPLS label)). FIBs 524 include lookuptables that map destination addresses to destination next hops. Thedestination addresses may include layer 3 network prefixes or layer 2MAC addresses. Flow tables 526 enable application of forwarding policiesto flows. Each of flow tables 526 includes flow table entries that eachmatch one or more flows that may traverse virtual router forwardingplane 528 and include a forwarding policy for application to matchingflows. For example, virtual router forwarding plane 528 attempts tomatch packets processed by routing instance 522A to one of the flowtable entries of flow table 526A. If a matching flow table entry existsfor a given packet, virtual router forwarding plane 528 applies the flowactions specified in a policy to the packet. This may be referred to as“fast-path” packet processing. If a matching flow table entry does notexist for the packet, the packet may represent an initial packet for anew packet flow and virtual router forwarding plane 528 may request VNagent 535 to install a flow table entry in the flow table for the newpacket flow. This may be referred to as “slow-path” packet processingfor initial packets of packet flows and is represented in FIG. 5 by slowpath 540.

In this example, VN agent 535 may be a user space 511 process executedby computing device 500. VN agent 535 includes configuration data 534,virtual routing and forwarding instances configurations 536 (“VRFs536”), and policy table 538 (“policies 538”). VN agent 535 exchangescontrol information with one or more SDN controllers (e.g., SDNcontroller 23 of FIGS. 1-3 ). Control information may include, virtualnetwork routes, low-level configuration state such as routing instancesand forwarding policy for installation to configuration data 534, VRFs536, and policies 538. VN agent 535 may also report analytics state,install forwarding state to FIBs 524 of virtual router forwarding plane528, discover VMs 510 and attributes thereof. As noted above, VN agent535 further applies slow-path packet processing for the first (initial)packet of each new flow traversing virtual router forwarding plane 528and installs corresponding flow entries to flow tables 526 for the newflows for fast path processing by virtual router forwarding plane 528for subsequent packets of the flows.

VN agent 35 further includes tag database 541. As described above,policy controller 25 of SDN controller 23 assigns one or more tagsspecifying one or more categories for the objects (and in some instanceone or more levels). Policy controller 25 may apply tags to objectsacross a plurality of categories (as well as apply the tags to objectsacross a plurality of levels and/or data centers). Policy controller 25distributes these tags to VN agent 535, which stores the assigned tagsin tag database 541.

As one example, an administrator may use policy controller 25 may applytags to projects, virtual machines, virtual networks, virtual machineinterfaces (e.g., ports) of computing devices, including computingdevice 500, that indicate whether the tagged objects are to redirectnetwork traffic to a host-based firewall. Policy agent 539 of VN agent535 may receive the tags from policy controller 25 and store the tags intag database 541.

The administrator may also use policy controller 25 to create one ormore policies expressed in terms of the tags to control network trafficbetween tagged objects. Policy agent 539 receives, from policycontroller 25, the one or more security policies and stores suchpolicies in policies 538. Each of policies 538 may include one or morepolicy rules that specify whether to redirect network traffic to a HBF.

The administrator (or another user) may use security controller 27 tocreate one or more firewall policies for the HBF. The HBF receives, viaa management interface of the HBF and from a security controller 27, theone or more firewall policies. Each of these policies may include one ormore functions of HBF instances for an application workload.

Each security policy and firewall policy may include one or more tagsthat specify to which objects, such as types of application workloadsexecuting on VMs 510, the policies apply. For example, policy agent 539may cross reference the one or more tags of the security policy andfirewall policy with one or more tags in tag database 541 to determineone or more objects to which the security policy and firewall policyshould be applied. Upon determining the one or more objects to which thesecurity policy and firewall policy should be applied, policy agent 139redirects network traffic to the HBF from one or more tagged objects inaccordance with the security policy, and the HBF applies a function ofthe HBF in accordance with the firewall policy.

FIG. 6 is a flowchart illustrating an example operation in accordancewith the techniques of the disclosure. For convenience, FIG. 6 isdescribed with respect to FIGS. 1 and 2 .

In the example of FIG. 6 , SDN controller 23 receives a security policyexpressed as one or more tags to redirect traffic of a virtualizedapplication workload to a host-based firewall (HBF) of the multi-tenantvirtualized data center (602). For example, a user may use policycontroller 25 of SDN controller 23 to define a security policy expressedin terms of one or more tags. The SDN controller 23 configures networkconnectivity to HBF 11A in accordance with the security policy (604).For example, policy controller 25 of SDN controller 23 may push thesecurity policy to policy agent 139A of VN agent 35A to apply thesecurity policies to tagged objects that are members of categories ofthe application workload to redirect traffic to HBF 11A. Based on thepolicy rule, policy agent 139A maps the tags to ports of VM4 36 thatimplements the HBF to redirect traffic to the HBF.

In some examples, policy agent 139A may communicate tenant informationand the tag-to-port mapping to SDN controller 23, which stores it in aconfiguration database. Security controller 27 may obtain the one ormore tags from SDN controller 23 (606). For example, security controller27 may use BGP to obtain the tenant information and the tag-to-portmapping from policy controller 25 of SDN controller 23.

Security controller 27 may receive one or more firewall policiesexpressed in terms of the one or more tags (608). For example, theadministrator may use security controller 27 to configure the HBF toprovide functions for various traffic types of the application workload.As one example, the administrator may specify HBF 11A to provide an IPSfor HTTPs traffic of the finance application workload. In anotherexample, the administrator may specify HBF 11A to provide malwareprotection for HTTP traffic of the finance application workload.Security controller 27 may push the firewall policies, using XMPP orNETCONF, for example, to a management interface of the HBF to configurethe HBF to provide the various functions of HBF 11A in accordance withthe one or more firewall policies (610). As one example, HBF 11Areceives, from security controller 27, a first firewall policy toimplement an IPS that blocks malicious HTTPs network traffic of afinance application workload. HBF 11A is then configured to apply theIPS, which may, for example, perform signature-based detection andstatistical anomaly-based detection mechanisms of an IPS to traffic ofthe finance application workload.

As another example, HBF 11A receives, from security controller 27, asecond firewall policy to implement malware protection for HTTP trafficof the finance application workload. HBF 11A is then configured to applythe malware protection, which may, for example, perform signature-baseddetection using a database of known malware definitions to scan formalware. When HBF 11A detects a file that matches the malware signature,the malware protection may flag, quarantine, or remove the potentialmalware.

The techniques described in this disclosure may be implemented, at leastin part, in hardware, software, firmware or any combination thereof. Forexample, various aspects of the described techniques may be implementedwithin one or more processors, including one or more microprocessors,digital signal processors (DSPs), application specific integratedcircuits (ASICs), field programmable gate arrays (FPGAs), or any otherequivalent integrated or discrete logic circuitry, as well as anycombinations of such components. The term “processor” or “processingcircuitry” may generally refer to any of the foregoing logic circuitry,alone or in combination with other logic circuitry, or any otherequivalent circuitry. A control unit comprising hardware may alsoperform one or more of the techniques of this disclosure.

Such hardware, software, and firmware may be implemented within the samedevice or within separate devices to support the various operations andfunctions described in this disclosure. In addition, any of thedescribed units, modules or components may be implemented together orseparately as discrete but interoperable logic devices. Depiction ofdifferent features as modules or units is intended to highlightdifferent functional aspects and does not necessarily imply that suchmodules or units must be realized by separate hardware or softwarecomponents. Rather, functionality associated with one or more modules orunits may be performed by separate hardware or software components, orintegrated within common or separate hardware or software components.

The techniques described in this disclosure may also be embodied orencoded in a computer-readable medium, such as a computer-readablestorage medium, containing instructions. Instructions embedded orencoded in a computer-readable storage medium may cause a programmableprocessor, or other processor, to perform the method, e.g., when theinstructions are executed. Computer readable storage media may includerandom access memory (RAM), read only memory (ROM), programmable readonly memory (PROM), erasable programmable read only memory (EPROM),electronically erasable programmable read only memory (EEPROM), flashmemory, a hard disk, a CD-ROM, a floppy disk, a cassette, magneticmedia, optical media, or other computer readable media.

Various examples have been described. These and other examples arewithin the scope of the following claims.

What is claimed is:
 1. A method comprising: receiving, by a softwaredefined networking (SDN) controller of a multi-tenant virtualized datacenter, a security policy expressed as one or more tags to redirecttraffic of a virtualized application workload to a host-based firewallof the multi-tenant virtualized data center; configuring, by the SDNcontroller, a virtual router to direct traffic of the virtualizedapplication workload to the host-based firewall in accordance with thesecurity policy; obtaining, by a security controller that manages thehost-based firewall, the one or more tags from the SDN controller;receiving, by the security controller, one or more firewall policiesexpressed in terms of the one or more tags, wherein each of the one ormore firewall policies specifies a function of the host-based firewall;and configuring, by the security controller, the function of thehost-based firewall in accordance with the one or more firewallpolicies.
 2. The method of claim 1, wherein the function of thehost-based firewall comprises at least one of Intrusion PreventionSystem, Intrusion Detection System, anti-virus, and malware detection.3. The method of claim 1, further comprising: configuring, by the SDNcontroller, a virtual execution element of a server of the multi-tenantvirtualized data center to implement the host-based firewall.
 4. Themethod of claim 3, wherein the virtual execution element comprises avirtual machine of the multi-tenant virtualized data center.
 5. Themethod of claim 3, wherein the virtual execution element comprises acontainer of a server of the multi-tenant virtualized data center. 6.The method of claim 1, further comprising: obtaining, by the securitycontroller, a virtual local area network (VLAN) identifier for one ormore tenants of the multi-tenant virtualized data center; andconfiguring, by the security controller, an instance of the host-basedfirewall for each of the one or more tenants of the multi-tenantvirtualized data center, wherein configuring the function of thehost-based firewall in accordance with the one or more firewall policiesfurther comprises configuring the one or more firewall policies usingthe one or more tags and the VLAN identifier for the one or more tenantsof the multi-tenant virtualized data center.
 7. The method of claim 1,further comprising: receiving, by the SDN controller, a request tocreate a project for the virtualized application workload to use thehost-based firewall; generating, by the SDN controller, a host-basedfirewall object to be specified in the security policy; in response togenerating the host-based firewall object, configuring, by the SDNcontroller, a left interface, a right interface, and a managementinterface for a virtual execution element implementing the host-basedfirewall; configuring, by the SDN controller, a left virtual network, aright virtual network, and a management network for the virtualexecution element implementing the host-based firewall; associating, bythe SDN controller, the left interface with the left virtual network;associating, by the SDN controller, the right interface with the rightvirtual network; and associating, by the SDN controller, the managementinterface with the management virtual network, wherein configuringnetwork connectivity to the host-based firewall in accordance with thesecurity policy comprises configuring network connectivity to the leftvirtual network and the right virtual network for the virtual executionelement implementing the host-based firewall.
 8. The method of claim 1,further comprising: in response to obtaining the one or more tags fromthe SDN controller, converting, by the security controller, the tags toIP addresses, wherein, to configure the function of the host-basedfirewall in accordance with the one or more firewall policies, thesecurity controller is configured to configure the function of thehost-based firewall based on the IP addresses.
 9. A system comprising: asoftware defined networking (SDN) controller of a multi-tenantvirtualized data center, the SDN controller configured to: receive asecurity policy expressed as one or more tags to redirect traffic of avirtualized application workload to a host-based firewall of themulti-tenant virtualized data center; and configure network connectivityto the host-based firewall in accordance with the security policy; and asecurity controller that manages the host-based firewall, the securitycontroller configured to: obtain the one or more tags from the SDNcontroller; receive one or more firewall policies expressed in terms ofthe one or more tags, wherein each of the one or more firewall policiesspecifies a function of the host-based firewall; and configure thefunction of the host-based firewall in accordance with the one or morefirewall policies.
 10. The system of claim 9, wherein the function ofthe host-based firewall comprises at least one of Intrusion PreventionSystem, Intrusion Detection System, anti-virus, and malware detection.11. The system of claim 9, further comprising: a virtual executionelement of a server of the multi-tenant virtualized data center, thevirtual execution element implemented as the host-based firewall. 12.The system of claim 11, wherein the virtual execution element comprisesa virtual machine of the multi-tenant virtualized data center.
 13. Thesystem of claim 11, wherein the virtual execution element comprises acontainer of a server of the multi-tenant virtualized data center. 14.The system of claim 9, wherein the security controller is furtherconfigured to: obtain an identifier for one or more tenants of themulti-tenant virtualized data center; and configure an instance of thehost-based firewall for each of the one or more tenants of themulti-tenant virtualized data center, wherein, to configure the functionof the host-based firewall in accordance with the one or more firewallpolicies, the security controller is further configured to configure theone or more firewall policies using the one or more tags and theidentifier for the one or more tenants of the multi-tenant virtualizeddata center.
 15. The system of claim 14, wherein the identifier for theone or more tenants of the multi-tenant virtualized data centercomprises a virtual local area network (VLAN) identifier.
 16. The systemof claim 9, wherein the SDN controller is further configured to: receivea request to create a project for the virtualized application workloadto use the host-based firewall; generate a host-based firewall object tobe specified in the security policy; in response to generating thehost-based firewall object, configure a left interface, a rightinterface, and a management interface for a virtual execution elementimplementing the host-based firewall; configure a left virtual network,a right virtual network, and a management network for the virtualexecution element implementing the host-based firewall; associate theleft interface with the left virtual network; associate the rightinterface with the right virtual network; and associate the managementinterface with the management virtual network, wherein, to configurenetwork connectivity to the host-based firewall in accordance with thesecurity policy, the SDN controller is further configured to configurenetwork connectivity to the left virtual network and the right virtualnetwork for the virtual execution element implementing the host-basedfirewall.
 17. The system of claim 9, wherein the security controller isfurther configured to: in response to obtaining the one or more tagsfrom the SDN controller, convert the tags to IP addresses, wherein, toconfigure the function of the host-based firewall in accordance with theone or more firewall policies, the security controller is configured toconfigure the function of the host-based firewall based on the IPaddresses.
 18. A non-transitory computer-readable medium comprisinginstructions that, when executed, cause one or more processors of amulti-tenant virtualized data center to: receive a security policyexpressed as one or more tags to redirect traffic of a virtualizedapplication workload to a host-based firewall of the multi-tenantvirtualized data center; configure network connectivity to thehost-based firewall in accordance with the security policy; receive oneor more firewall policies expressed in terms of the one or more tags,wherein each of the one or more firewall policies specifies a functionof the host-based firewall; and configure the function of the host-basedfirewall in accordance with the one or more firewall policies.
 19. Thenon-transitory computer-readable medium of claim 18, wherein theinstructions further cause the one or more processors to: configure avirtual execution element of a server of the multi-tenant virtualizeddata center to implement the host-based firewall, wherein the functionof the host-based firewall comprises at least one of IntrusionPrevention System, Intrusion Detection System, anti-virus, and malwaredetection, and wherein the virtual execution element comprises a virtualmachine or a container of the multi-tenant virtualized data center. 20.The non-transitory computer-readable medium of claim 18, wherein theinstructions further cause the one or more processors to: receive arequest to create a project for the virtualized application workload touse the host-based firewall; generate a host-based firewall object to bespecified in the security policy; in response to generating thehost-based firewall object, configure a left interface, a rightinterface, and a management interface for a virtual execution elementimplementing the host-based firewall; configure a left virtual network,a right virtual network, and a management network for the virtualexecution element implementing the host-based firewall; associate theleft interface with the left virtual network; associate the rightinterface with the right virtual network; and associate the managementinterface with the management virtual network, wherein, to configurenetwork connectivity to the host-based firewall in accordance with thesecurity policy, the instructions cause the one or more processors toconfigure network connectivity to the left virtual network and the rightvirtual network for the virtual execution element implementing thehost-based firewall.